By Marcy Stamper
Engineers, fish biologists and construction teams who scrambled to meet an April 15 deadline to devise a way to move the first of an expected 20,000 spring Chinook salmon over the fractured Wanapum Dam say they have met their initial goals.
Construction workers have retrofitted the fish ladders at the dam, 150 miles from upstream spawning grounds in Methow Valley rivers and streams, with pumps and an exit flume, according to the Grant County Public Utility District (PUD), which operates the dam.
As of last Wednesday (April 23), 31 spring Chinook and 270 steelhead had successfully ascended one of the fish ladders at the dam, which was retrofitted with a flume that gives the fish a gradual descent into the reservoir, according to Chuck Allen, public affairs officer for the PUD. Modifications to the second fish ladder were completed last weekend.
The modifications are necessary because the water level in the reservoir was reduced 26 feet—too far for fish to jump—to allow engineers to examine a crack in the dam that was discovered in February. They are still evaluating the fracture and how to address the problem.
An additional 101 fish—74 spring Chinook and 27 steelhead—have been ferried around the dam by truck. Workers for the Washington Department of Fish and Wildlife (WDFW) are capturing all fish at Priest Rapids Dam, 19 miles downstream of Wanapum, and trucking the wild fish. Most hatchery fish are being released back into the river to make the trip on their own, said Allen.
Fish managers also plan to tag 250 of the captured hatchery fish so they can monitor their progress through Wanapum and upstream dams, said Allen. So far, they have tagged 41. They are providing fish tallies every Wednesday.
Plans call for trapping and hauling fish for at least another week until managers are sure the modified fish ladders are working properly, said Allen. Thus far there have been no instances where a fish has entered a ladder and not been observed swimming away at the other end, said Allen.
The number of fish that passed through the fish ladders between April 15 and 23 is actually higher than it was last year, since most of the fish that crossed the dam arrived early and were waiting below Wanapum until they could get through, said Allen. Fish managers don’t start counting fish until April 15, when the spring Chinook run starts to pick up.
“The important thing to remember is that the numbers are skewed, since there was no fish passage at Wanapum from the end of February through April 15,” said Allen.
While biologists say hauling fish could work to move the endangered spring Chinook—which can reach 1,500 per day at peak—they acknowledge that the much larger runs of summer Chinook, sockeye and steelhead, which begin in June and can top 12,000 fish per day, require functional fish ladders, according to WDFW. The agency has eight tanker trucks to move the salmon, each capable of moving up to 1,500 fish a day.
Salmon managers are anticipating 80,000 summer Chinook, 400,000 sockeye and 300,000 fall Chinook. “But there simply aren’t enough trucks, trained personnel, or hours in the day to move the number of salmon we’re expecting later in the year,” said Jim Brown, WDFW’s regional director.
After passing through Wanapum, it takes the spring Chinook at least two more weeks before they traverse the last three dams and reach the Methow River, according to Charlie Snow, a fish biologist with WDFW.
Fish biologists have been worried not only about the impact on spring Chinook, but also about half a dozen other species of salmon, both endangered and non-listed, that return to the Methow, Twisp and Chewuch rivers and their tributaries to spawn.
If the fish don’t make it to their spawning grounds to lay eggs, it would have serious consequences for future generations, since females of most species lay between 3,000 and 7,000 eggs each, said Snow.
The temporary solution for migrating fish became necessary after a horizontal fracture 65 feet long and up to 2 inches wide was found in a spillway pier at Wanapum Dam in late February. The PUD estimate the cost of investigating and repairing the fracture and modifying the fish ladders at $61 million.